Inorganic pyrophosphatase (PPase) [2160278, 1323891] is the enzyme responsible for the hydrolysis of pyrophosphate (PPi) which is formed principally as the product of the many biosynthetic reactions that utilise ATP. All known PPases require the presence of divalent metal cations, with magnesium conferring the highest activity. Among other residues, a lysine has been postulated to be part of or close to the active site. PPases have been sequenced from bacteria such as Escherichia coli (homohexamer), Bacillus PS3 (Thermophilic bacterium PS-3) and Thermus thermophilus, from the archaebacteria Thermoplasma acidophilum, from fungi (homodimer), from a plant, and from bovine retina. In yeast, a mitochondrial isoform of PPase has been characterised which seems to be involved in energy production and whose activity is stimulated by uncouplers of ATP synthesis.

The sequences of PPases share some regions of similarities, among which is a region that contains three conserved aspartates that are involved in the binding of cations.

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry
out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 6 models
in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical
are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have
different domain combinations including a Inorganic pyrophosphatase domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

There are 6 hidden Markov models representing the Inorganic pyrophosphatase superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.